The communications industry is rapidly changing to adjust to emerging technologies and ever increasing customer demand. This customer demand for new applications and increased performance of existing applications is driving communications network and system providers to employ networks and systems having greater speed and capacity (e.g., greater bandwidth). In trying to achieve these goals, a common approach taken by many communications providers is to use packet switching technology.
Bit Index Explicit Replication (BIER) is an architecture for the forwarding of multicast data packets in a network. It provides optimal forwarding of multicast packets through a “multicast domain.” However, it does not require any explicit tree-building protocol, nor does it require intermediate nodes to maintain any per-flow state. When a multicast data packet enters the domain, the ingress router determines the set of egress routers to which the packet needs to be sent. The ingress router then encapsulates the packet in a BIER header. The BIER header contains a bit string in which each bit represents exactly one egress router in the domain; to forward the packet to a given set of egress routers, the bits corresponding to those routers are set in the BIER header. Elimination of the per-flow state and the explicit tree-building protocols results in a considerable simplification.